We showed previously that fibril formation in vitro from rat tail tendon collagen requires a temperaturedependent initiation (Step 1) following which linear assembly to form thin filaments (Step 2) proceeds as rapidly at 4°C as at 26°C. Step 3, lateral assembly of filaments to form fibrils, is again temperature-dependent. We now find that Step 1 is complete in 6 min at 26°C and the time is independent of collagen concentration in the range 0.08 to 0.39 mg/ml. Collagen treated with pepsin, which… CONTINUE READING